A contract to be made by an agent on behalf of a principal is considered to be the contract of the principal and not that of the agent. It allows the principal to approve somebody to carry out her duties, either for a precise purpose or generally (i.e., to conduct transactions). The agency relationship is typically entered into by informal agreement, but also can occur by formal agreement (in certain cases, the agency affiliation must be specified in writing).
The current wireless and locationing technologies, with their improved speed of data and location capabilities provide new opportunities for business growth by enhancing integration between business with physical premises and internet based commerce. General wireless technologies such as cellular, WLAN, Bluetooth, ZigBee, RF-ID and other positioning technologies like GPS, databases mapping base stations and access point, multilateration and other technologies provide a method for taking advantage of proximity between users of wireless devices.
A geo-fence is a virtual perimeter for a real world geographic area. A geofence can be dynamically generated as in a radius around a point location that could be stationary or mobile. A geofence can be a predefined set of boundaries connecting points expressed by latitude and longitude, like neighborhood boundaries. Geofencing has been made possible by the introduction of locationing techniques like, for example, the GPS (Global Positioning System) technology or the multilateration technology and the miniaturization of electronic components that have made the GPS a standard feature in mobile phones and portable electronics in general (User Equipment).